This invention relates generally to electronically commutated motors (ECMs), and more particularly, to methods and systems for automatic determination of a rotation direction within electronically commutated motors.
Electronically commutated motors (ECMs) are used in a wide variety of applications because they are more efficient than known standard induction motors. ECMs include the efficiency and speed control advantages of a DC motor and minimize the disadvantages of DC motors, e.g., carbon brush wear, short life span, and noise. In Heating, Ventilation and Air Conditioning (HVAC) systems, as well as, known commercial air distributions systems, ECMs automatically adjust blower speed to meet a wide range of airflow requirements. Known ECMs use microprocessor technology to control fan speed, torque, air flow, and energy consumption.
As described above, ECM motors are generally utilized in air handling (blowers, fans) applications within HVAC systems. Blower wheels and housings are used in right and left hand configurations, i.e. clockwise and counter clockwise rotation. To minimize the motor models required by an OEM (Original Equipment Manufacturer) it is desirable to utilize a single motor to serve both blower rotation directions. Such a motor would also reduce errors caused by using several motor models when changing from a standard induction motor to an ECM. However, such a motor would also have a capability to detect the proper rotation direction for the blower in which it has been installed.
It is believed that some systems observe a coast-down of the blower to determine some data associated with a load for that blower which is then used to determine settings to be used in producing constant airflow. In other motor drives, the direction of rotation is changed either through communication to a motor drive computer or by changing the setting of a switch or placement of a jumper wire.